FKIE_CVE-2026-80630
Vulnerability from fkie_nvd - Published: 2026-08-28 08:16 - Updated: 2026-08-29 07:16
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved:
net/sched: sch_fq_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen
Whenever fq_codel drops packets during peek, it calls
qdisc_tree_reduce_backlog. An issue arises because it calls
qdisc_tree_reduce_backlog before it reincrements the qlen. If qlen drops
to zero, but peek returns an skb, the parent's qlen_notify callback will be
executed even though fq_codel still has 1 packet on the queue and, thus,
will mistakenly deactivate the parent's class causing issues like a recent
report [1] and a wild memory access in qfq:
[ 29.371146][ T360] Oops: general protection fault, probably for non-canonical address 0xfbd59c0000000024: 0000 [#1] SMP KASAN NOPTI
[ 29.371666][ T360] KASAN: maybe wild-memory-access in range [0xdead000000000120-0xdead000000000127]
[ 29.371987][ T360] CPU: 6 UID: 0 PID: 360 Comm: tc Not tainted 7.1.0-rc5-00285-gc530e5b2dbc6-dirty #82 PREEMPT(full)
[ 29.372384][ T360] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
[ 29.372620][ T360] RIP: 0010:qfq_deactivate_agg (include/linux/list.h:1029 (discriminator 2) include/linux/list.h:1043 (discriminator 2) net/sched/sch_qfq.c:1369 (discriminator 2) net/sched/sch_qfq.c:1395 (discriminator 2)) sch_qfq
[ 29.373544][ T360] RSP: 0018:ffff888102417370 EFLAGS: 00010216
[ 29.373800][ T360] RAX: 0000000000000000 RBX: ffff88811224d568 RCX: dffffc0000000000
[ 29.374079][ T360] RDX: 1ffff11021fe1543 RSI: ffff88810ff0aa00 RDI: dffffc0000000000
[ 29.374368][ T360] RBP: ffff88811224c280 R08: dead000000000122 R09: 1bd5a00000000024
[ 29.374649][ T360] R10: fffffbfff7940329 R11: fffffbfff7940329 R12: 0000000000000000
[ 29.374926][ T360] R13: dead000000000100 R14: ffff88811224d580 R15: ffff88811224d578
[ 29.375207][ T360] FS: 00007f5b794e5780(0000) GS:ffff88815d1e9000(0000) knlGS:0000000000000000
[ 29.375545][ T360] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 29.375823][ T360] CR2: 000055ffb091f000 CR3: 000000010a305000 CR4: 0000000000750ef0
[ 29.376103][ T360] PKRU: 55555554
[ 29.376258][ T360] Call Trace:
[ 29.376401][ T360] <TASK>
...
[ 29.376885][ T360] qfq_reset_qdisc (net/sched/sch_qfq.c:357 net/sched/sch_qfq.c:1487) sch_qfq
[ 29.377074][ T360] qdisc_reset (net/sched/sch_generic.c:1057)
[ 29.377414][ T360] __qdisc_destroy (net/sched/sch_generic.c:1096)
[ 29.377600][ T360] qdisc_graft (net/sched/sch_api.c:1062 net/sched/sch_api.c:1053 net/sched/sch_api.c:1159)
[ 29.378593][ T360] tc_get_qdisc (net/sched/sch_api.c:1528 net/sched/sch_api.c:1556)
Fix this by only calling qdisc_tree_reduce_backlog in peek after the
qlen is restored.
[1] http://lore.kernel.org/netdev/CAN2cbVe79oj0O9==m4+4x3v+O+qzRagA=2=wkrp9i9=CqYvyZA@mail.gmail.com/
References
Impacted products
| Vendor | Product | Version |
|---|
{
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/sched/sch_fq_codel.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "3e515188393e62a718ccebee651ee74514104ff6",
"status": "affected",
"version": "cc71a757da78dd4aa1b4a9b19cb011833730ccf2",
"versionType": "git"
},
{
"lessThan": "20dd591d8f951e1e6aca5052be8785e6181055e2",
"status": "affected",
"version": "eda741fe155ddf5ecd2dd3bfbd4fc3c0c7dbb450",
"versionType": "git"
},
{
"lessThan": "94a5f1efdefb01f82cd228bf4e7ef1e8fc075c80",
"status": "affected",
"version": "829c49b6b2ff45b043739168fd1245e4e1a91a30",
"versionType": "git"
},
{
"lessThan": "acc08a0c7f37ebb1901144e03a7cba7d4afd9203",
"status": "affected",
"version": "2f9761a94bae33d26e6a81b31b36e7d776d93dc1",
"versionType": "git"
},
{
"lessThan": "7c09843fd2b44d9bf0de798683861d1aecd62a08",
"status": "affected",
"version": "4d55144b12e742404bb3f8fee6038bafbf45619d",
"versionType": "git"
},
{
"lessThan": "0500af8630c3253f0dde879bd3a73a06bb2f2b3f",
"status": "affected",
"version": "342debc12183b51773b3345ba267e9263bdfaaef",
"versionType": "git"
},
{
"lessThan": "af54df2f44d9605614bc7ed96640302a240a9a62",
"status": "affected",
"version": "342debc12183b51773b3345ba267e9263bdfaaef",
"versionType": "git"
},
{
"lessThan": "097f6fc7b1ae362dd7a9444b2572162fda73b284",
"status": "affected",
"version": "342debc12183b51773b3345ba267e9263bdfaaef",
"versionType": "git"
},
{
"status": "affected",
"version": "7a742a9506849d1c1aa71e36c89855ceddc7d58e",
"versionType": "git"
},
{
"status": "affected",
"version": "e73c838c80dccb9e4f19becc11d9f3cb4a27d483",
"versionType": "git"
},
{
"status": "affected",
"version": "a57fe60ef4cf96bfbb6b58397ec28bdb5a5c6b31",
"versionType": "git"
},
{
"lessThan": "5.10.261",
"status": "affected",
"version": "5.10.241",
"versionType": "semver"
},
{
"lessThan": "5.15.212",
"status": "affected",
"version": "5.15.190",
"versionType": "semver"
},
{
"lessThan": "6.1.178",
"status": "affected",
"version": "6.1.135",
"versionType": "semver"
},
{
"lessThan": "6.6.145",
"status": "affected",
"version": "6.6.88",
"versionType": "semver"
},
{
"lessThan": "6.12.97",
"status": "affected",
"version": "6.12.24",
"versionType": "semver"
},
{
"lessThan": "5.5",
"status": "affected",
"version": "5.4.297",
"versionType": "semver"
},
{
"lessThan": "6.14",
"status": "affected",
"version": "6.13.12",
"versionType": "semver"
},
{
"lessThan": "6.15",
"status": "affected",
"version": "6.14.3",
"versionType": "semver"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/sched/sch_fq_codel.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "6.15"
},
{
"lessThan": "6.15",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.261",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.212",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.178",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.145",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.97",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.40",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.1.*",
"status": "unaffected",
"version": "7.1.5",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix"
}
]
}
],
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: sch_fq_codel: Do not call qdisc_tree_reduce_backlog during peek before restoring qlen\n\nWhenever fq_codel drops packets during peek, it calls\nqdisc_tree_reduce_backlog. An issue arises because it calls\nqdisc_tree_reduce_backlog before it reincrements the qlen. If qlen drops\nto zero, but peek returns an skb, the parent\u0027s qlen_notify callback will be\nexecuted even though fq_codel still has 1 packet on the queue and, thus,\nwill mistakenly deactivate the parent\u0027s class causing issues like a recent\nreport [1] and a wild memory access in qfq:\n\n[ 29.371146][ T360] Oops: general protection fault, probably for non-canonical address 0xfbd59c0000000024: 0000 [#1] SMP KASAN NOPTI\n[ 29.371666][ T360] KASAN: maybe wild-memory-access in range [0xdead000000000120-0xdead000000000127]\n[ 29.371987][ T360] CPU: 6 UID: 0 PID: 360 Comm: tc Not tainted 7.1.0-rc5-00285-gc530e5b2dbc6-dirty #82 PREEMPT(full)\n[ 29.372384][ T360] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011\n[ 29.372620][ T360] RIP: 0010:qfq_deactivate_agg (include/linux/list.h:1029 (discriminator 2) include/linux/list.h:1043 (discriminator 2) net/sched/sch_qfq.c:1369 (discriminator 2) net/sched/sch_qfq.c:1395 (discriminator 2)) sch_qfq\n[ 29.373544][ T360] RSP: 0018:ffff888102417370 EFLAGS: 00010216\n[ 29.373800][ T360] RAX: 0000000000000000 RBX: ffff88811224d568 RCX: dffffc0000000000\n[ 29.374079][ T360] RDX: 1ffff11021fe1543 RSI: ffff88810ff0aa00 RDI: dffffc0000000000\n[ 29.374368][ T360] RBP: ffff88811224c280 R08: dead000000000122 R09: 1bd5a00000000024\n[ 29.374649][ T360] R10: fffffbfff7940329 R11: fffffbfff7940329 R12: 0000000000000000\n[ 29.374926][ T360] R13: dead000000000100 R14: ffff88811224d580 R15: ffff88811224d578\n[ 29.375207][ T360] FS: 00007f5b794e5780(0000) GS:ffff88815d1e9000(0000) knlGS:0000000000000000\n[ 29.375545][ T360] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n[ 29.375823][ T360] CR2: 000055ffb091f000 CR3: 000000010a305000 CR4: 0000000000750ef0\n[ 29.376103][ T360] PKRU: 55555554\n[ 29.376258][ T360] Call Trace:\n[ 29.376401][ T360] \u003cTASK\u003e\n...\n[ 29.376885][ T360] qfq_reset_qdisc (net/sched/sch_qfq.c:357 net/sched/sch_qfq.c:1487) sch_qfq\n[ 29.377074][ T360] qdisc_reset (net/sched/sch_generic.c:1057)\n[ 29.377414][ T360] __qdisc_destroy (net/sched/sch_generic.c:1096)\n[ 29.377600][ T360] qdisc_graft (net/sched/sch_api.c:1062 net/sched/sch_api.c:1053 net/sched/sch_api.c:1159)\n[ 29.378593][ T360] tc_get_qdisc (net/sched/sch_api.c:1528 net/sched/sch_api.c:1556)\n\nFix this by only calling qdisc_tree_reduce_backlog in peek after the\nqlen is restored.\n\n[1] http://lore.kernel.org/netdev/CAN2cbVe79oj0O9==m4+4x3v+O+qzRagA=2=wkrp9i9=CqYvyZA@mail.gmail.com/"
}
],
"id": "CVE-2026-80630",
"lastModified": "2026-08-29T07:16:47.027",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 3.9,
"impactScore": 5.9,
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary"
}
]
},
"published": "2026-08-28T08:16:47.850",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/0500af8630c3253f0dde879bd3a73a06bb2f2b3f"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/097f6fc7b1ae362dd7a9444b2572162fda73b284"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/20dd591d8f951e1e6aca5052be8785e6181055e2"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/3e515188393e62a718ccebee651ee74514104ff6"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/7c09843fd2b44d9bf0de798683861d1aecd62a08"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/94a5f1efdefb01f82cd228bf4e7ef1e8fc075c80"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/acc08a0c7f37ebb1901144e03a7cba7d4afd9203"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/af54df2f44d9605614bc7ed96640302a240a9a62"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Received"
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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